The GP100 is their current full size gun. I have a discontinued Security Six. Kinda funny how things work some times. Ruger brought out the Security Six to be more robust than the S&W model 19’s, which they were. Then both S&W and Ruger came out with new models that were bigger yet almost back to the N frame S&W’s.
The original Ruger Security Six, Speed Six and Service Six all had great reputations for durability. I’m not knocking the new guns by either mfg though. I loved my Model 27. Big 357’s are easy to shoot.